Seasonal Depression and Light Therapy in Winter

Seasonal depression, often called seasonal affective disorder (SAD), is a depression that occurs each year at the same time, usually starting in fall or winter and ending in spring or early summer. It is more than just “the winter blues” or “cabin fever.” A rare form of SAD known as “summer depression,” begins in late spring or early summer and ends in fall.

People who suffer from SAD have many of the common signs of depression: Sadness, anxiety, irritability, loss of interest in their usual activities, withdrawal from social activities, and inability to concentrate. They often have symptoms such as extreme fatigue and lack of energy, increased need for sleep, craving for carbohydrates, and increased appetite and weight gain.

Symptoms of winter SAD include:

Increased need for sleep
Decreased levels of energy
Weight gain
Increase in appetite
Difficulty concentrating
Increased desire to be alone
Symptoms of summer SAD include:
Weight loss
Trouble sleeping
Decreased appetite

How Common Is SAD?

Between 4%-6% of the U.S. population suffers from SAD, while 10%-20% may suffer from a more mild form of winter blues. Three-quarters of the sufferers are women, most of whom are in their 20s, 30s, and 40s. Though SAD is most common during these ages, it can also occur in children and adolescents. Older adults are less likely to experience SAD.
This illness is more commonly seen in people who live at high latitudes (geographic locations farther north or south of the equator), where seasonal changes are more extreme. It is estimated that 1% of Florida residents, 4% of Washington, D.C., residents, and nearly 10% of Alaska residents suffer from SAD.

What Causes SAD?

The exact cause of this condition is not known, but the influence of latitude on SAD strongly suggests that it is caused by changes in the availability of sunlight. One theory is that with decreased exposure to sunlight, the biological clock that regulates mood, sleep, and hormones is delayed, running more slowly in winter. Exposure to light may reset the biological clock.

Another theory is that brain chemicals that transmit information between nerves, called neurotransmitters (for example, serotonin), may be altered in individuals with SAD. It is believed that exposure to light can correct these imbalances.

How Can I Tell If I Have SAD?

It is very important that you do not diagnose yourself. If you have symptoms of depression, see your doctor for a thorough assessment. Sometimes physical problems can cause depression. But other times, symptoms of SAD are part of a more complex psychiatric problem. A health professional should be the one to determine the level of depression and recommend the right form of treatment.

How Is SAD Treated?

Research now shows that light therapy is an effective treatment for SAD. Sometimes antidepressant medicine is used alone, or in combination with light therapy. Spending time outdoors during the day can be helpful, as well as maximizing the amount of sunlight you’re exposed to at home and in the office.

What Is Light Therapy, And Is It Safe?

Light therapy, sometimes called phototherapy, is administered by a device that contains white fluorescent light tubes covered with a plastic screen to block ultraviolet rays. The intensity of light emitted (Lux) should be at least 10,000 Lux. The patient does not need to look directly into the light, but reads or eats while sitting in front of the device at a distance of 2 to 3 feet. Light therapy is safe and generally well tolerated.

Minor side effects of light therapy include:

Eye strain

At What Time of the Day and for How Long Should I Use Light Therapy?

Recent studies suggest that morning light therapy is more effective than evening treatments. Using this treatment too late in the day may also produce insomnia. Many health professionals today prefer to treat SAD with 10,000 Lux for 30 minutes every morning. Patients have shown some improvement within 2 to 4 days and reach full benefits within 2 to 4 weeks. The symptoms of SAD return quickly after discontinuation of light therapy, so light treatment should be continued throughout the entire season of low sunlight.

Even though they generate enough light, tanning beds should not be used to treat SAD. The amount of ultraviolet (UV) rays they produce is harmful to the skin and eyes.

Can I Prevent the Onset of SAD?

If you or someone you know has the symptoms of SAD, see your doctor for a thorough examination. You want to make sure that these symptoms are not caused by another form of depression or major medical illness. Other types of depression can result in harm and even suicide.

If you have been diagnosed with SAD, here are some things you can do to help to prevent it from coming back:

Try to spend some amount of time outside every day, even when it’s very cloudy. The effects of daylight are still beneficial.
Begin using a light box upon the onset of low sunlight (fall season), even before you feel the onset of winter SAD.
Eat a well-balanced diet, including sufficient amounts of vitamins and minerals as recommended by the FDA. This will help you have more energy even though your body is craving starchy and sweet foods.
Try exercising for 30 minutes a day, three times a week.
Seek professional counseling, if needed, during the winter months.
Stay involved with your social circle and regular activities. This can be a tremendous means of support during winter months.

Most recent estimates say about 10 million Americans suffer from seasonal depression and another 25 million have milder versions.

Lack of light has always had an effect on human beings. Like other animals, humans respond to darkness by producing more melatonin, which acts like a tranquilizer on the body. In just an hour of darkness, we can produce five times as much melatonin as during daylight hours. At sunrise, the bright light ordinarily causes the body to stop producing melatonin, but in the winter not enough light is received to trigger the signal to stop production.

For most people, the negative aspects of winter are annoying, but not a problem. However, people with a condition known as SAD, or seasonal affective disorder suffer from more serious symptoms. This malady is four times as common in women as in men. This disorder was first identified fifteen years ago by Norman Rosenthal, M.D. at the National Institute of Mental Health. Since then, scientists have continued to learn more about SAD and it’s effects. A milder form is known as the “winter blues.”

Although SAD often begins in the late twenties, children and teenagers are also at risk. A genetic component may be involved, with most SAD sufferers having at least one close relative with a history of depression. Interestingly, the incidence increases with distance from the equator, although those who live in areas with a great deal of snow are less likely to suffer from the illness.

Individuals who suffer from SAD often experience sleep difficulties. These include problems getting up in the morning, sleeping more but not feeling refreshed upon waking and daytime drowsiness. They may have a decrease in deep sleep called slow-wave sleep causes interrupted and lower-quality sleep.

Another common symptom is changes in eating habits. SAD sufferers report increased carbohydrate cravings during the winter months, often accompanied by weight gain.

While some women experience premenstrual syndrome year round, other say they intensify in the winter months.
Depression is a also symptom of SAD. Sufferers may have heightened anxiety and feelings of guilt, difficulty completing tasks, diminished sex drive and feelings of despair.

The good news is SAD is treatable in most people and light therapy is the preferred treatment. This involves exposing the eyes to daily periods of light in the form of a light box. While the standard for light boxes is full-spectrum florescent lighting, studies indicate intensity, rather than the type of light, determines the success rate. The light must be bright, at least five times brighter than a well-lit office, for example. During a session, the individual sits in front of the light box with lights on and eyes open. It’s not necessary to look directly at the light. Most people show improvements by using the light box in fifteen to thirty minute increments.

Light boxes designed for this purpose are available without a prescription for between $300-$600. However, if you’re symptoms are serious enough to require a light box, you should first seek advice from a physician.

At least three recent studies have been conducted on bright light and it’s effectiveness on SAD. In all three cases, the experiments focused on which time of day was best for light therapy.

The results tend to confirm the theory that in most cases, SAD seems to be caused by a delay in the timing of events governed bycircadian (24-hour) biological rhythms, including secretion of the sleep promoting hormone melatonin. Morning light, as opposed to evening, is believed to best counteract the symptoms of SAD, by advancing the whole cycle to an earlier time of day. In the studies, three quarters of SAD sufferers responded well to the morning light therapy.

If you think you might have full-blown SAD, see your physician. If your case is mild, here are some ways to beat those winter blahs:

1. Go to the tanning bed twice a week, for ten minutes sessions. Vanity aside, tanning is beneficial because it brings much needed light into your environment. Light therapy has a proven high success rate with serious SAD suffers and it can help others as well.

2. Make time for morning or mid-day walks. The walks need not be long or arduous. The important thing is to combine the precious daylight with the benefits of exercise.

3. Look up a friend you haven’t seen in years. In the fall, before the cold sets in, plan a three day weekend in January or February to visit your friend. It gives you both something enjoyable to anticipate.

4. Reduce your fat intake. High-fat meals fill the bloodstream with fat, making less oxygen available to the brain. Remember all your relatives who retreat to the couch for a nap after a holiday feast? Choose a protein or carbohydrate-rich diet.

5. Move your summer vacation to the winter. Interrupt the worst stretch of winter at a sunny beach in mid-January. Nothing improves an attitude and recharges the battery like new sights and a warm climate, while others at home are shoveling snow!

6. Visit local sights. Have you always wanted to visit that local art gallery or historical museum? Winter weekends are the perfect time. Set a goal to be a tourist in your own town and recruit a friend or family member to tag along. Ordinary, humdrum weekends will be a thing of the past.

7. Volunteer each week. Few things can alter a sagging attitude like volunteering. Deliver groceries to the homebound or work at the homeless shelter. You’ll soon be counting your blessings and spending less time as a couch potato.

8. Start a new hobby. Winter is a great time to start something completely new and different. You’ll be eager to get home from work to delve into your stained glass project, watercolor painting, candle-making or ballroom dancing practice. Pamper yourself with that valuable gift of time to do as you please.

SAD (Seasonal Affective Disorder) is a type of winter depression which affects millions of people every winter between September and April, in particular during December, January and February. SAD is caused by a biochemical imbalance in the hypothalamus due to the shortening of daylight hours and the lack of sunlight in winter. For many people SAD is a seriously disabling illness, preventing them from functioning normally without continuous medical treatment. For others, it is a milder condition, causing discomfort, referred to as sub-syndromal SAD or winter blues. There is also a rare reverse form of SAD, known as summer SAD, where symptoms occur each summer and remit in winter.

SAD symptoms usually reoccur regularly each winter, starting between September and November and continuing until March or April; a diagnosis can be made after 2 or more consecutive winters of symptoms. In sub-syndromal SAD, symptoms such as tiredness, lethargy, sleep and eating problems occur, but depression and anxiety are absent or mild.

SAD symptoms disappear in spring, either suddenly with a few weeks of hypomania/hyperactivity, or gradually, depending on the intensity of sunlight in the spring/early summer. In summer SAD, symptoms may be related to excessive heat rather than light and may include irritability and lethargy rather than oversleeping and overeating.

SAD may begin at any age, but the main age of onset is 18-30. It occurs throughout the northern and southern hemispheres but is rare in those living within 30 degrees of the Equator, where daylight hours are long, constant and extremely bright.


Light therapy has been proven effective in over 80% of diagnosed cases, with exposure from 30 minutes to several hours per day to very bright light, at least 10 times the intensity of ordinary domestic lighting. Ordinary light bulbs and fittings are not strong enough. Whereas the average home or office lighting deliver an intensity of 200-500 lux, the minimum dose necessary to treat SAD is 2500 lux. Some light units deliver up to 10,000 lux, which can shorten treatment time.

Light treatment should be used daily in winter, starting in early autumn when the first symptoms appear. It consists of sitting 2-3 feet away from a specially designed light box, wearing a Light Visor, or waking up to dawn simulator. Allow the light to shine on the eyes. While getting your light treatment carry out normal duties; eating, writing, reading, etc. It is not necessary to stare at the light during the session, but keep in mind that the more photons that reach the retina, the faster the session will be.

Treatment is usually effective within 3-4 days and the effect continues provided it is used every day. Sun glasses, tinted lenses, or any device which blocks the light to the Retina of the eye, should not be worn. Daily exposure to as much natural daylight as possible can be of help.

When it comes time to shop for a light unit, be a smart consumer and shop around. Weigh the pros and cons of the different products and different companies. Product economy is one factor, but product quality and company service are even more important. All reputable companies will offer a return system if the light doesn’t work for you.

Traditional antidepressant drugs such as tricyclics are not usually helpful for SAD as they may exacerbate sleepiness and lethargy. The non-sedative SSRI drugs such as paroxetine (Seroxat), sertraline(Lustral) and fluoxetine (Prozac) are effective in helping the depressive symptoms of SAD and combine well with light therapy. Other psychotropic drugs (i.e. lithium, benzodiazepines) have not proven very useful in the treatment of SAD.

Psychotherapy, counseling or any similar therapy which helps the person with SAD to relax, accept their illness and cope with its limitations can be useful.

Who is NOSAD?

The National Organization for Seasonal Affective Disorder (NOSAD) is a small non-profit organization dedicated to helping people affected by SAD find support and treatment for their illness.

The primary feature of seasonal affective disorder is a pattern of depressive or manic episodes that occurs with the onset of the winter months. As the days become shorter, and the weather colder, there is an increase in vegetative depressive symptoms. Individuals eat more, crave carbohydrates, sleep more, experience chronic fatigue and gain weight. In pronounced cases, significant social withdrawal occurs as well. Some have described the pattern as a hibernation during the winter months.

The second phase of the disorder, is the tendency for these symptoms to abate once the days become longer and warmer in the Spring. Again, the hibernation analogy works well. Finally, this pattern of seasonal depression must be present for at least two consecutive years, without any occurrences of non-seasonal depression Researchers are still trying to determine if this is a separate disorder, or simply the manifestation of recurrent major depression or another mood disorder in a cycle pattern. Is the depression caused by a decrease in sunlight, by colder weather, or by the increased isolation and stress of coping with the winter months? There is some indication that sunlight, entering through the retina, stimulates the production of chemicals in the brain that have an antidepressant effect, but many questions remain unanswered. Because both biological and physical factors appear to play a role in most depression, it is difficult to develop an experimental study that will control for all other relevant variables to produce definitive answers. Meanwhile, those who become depressed in the winter months want to know what they can do to combat this depression.

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